Epidemiologist Cara Halldin supervises the coal workers’ health surveillance program for NIOSH, and is one of the study authors. She said the cases are concentrated among miners in Kentucky, Virginia, and West Virginia.

“In the U.S. it’s about 1 in 10, in Central Appalachia it’s about 1 in 5, which is really concerning,” Halldin said.

An X ray image of an Appalachian coal miner with black lung lesions.

Credit Adelina Lancianese / NPR

The study, published in the American Journal of Public Health, focused on active, underground miners with 25 or more years of experience. Only miners who participated in the surveillance program were included, Halldin said, so it is possible that the rates of black lung could be much higher.

The disease is caused by exposure to coal dust, which federal regulations require the mining industry to control.

“But this much disease suggests that miners are being exposed to way too much dust,” Halldin said.